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Pittsburg and Midway Coal Company Edna Mine Water Quality Assessment CO-0032638 <br />Table A-8 <br />Ambient Water Quality for Trout Creek <br />for the Autide radatiou Review <br /> <br />Paramefer .` <br />k , ; tVum6er of <br />, : <br />Samples <br />,,, 15th <br /> <br />'Percentile 50th . <br /> <br />'Percentile = 85th <br />'-. <br />Percentile <br />. 'Mean Chontc <br />~ Sfream.' <br />.Standard , <br />11{oles,' <br />As, Dis u 7 1.0 1.0 1.0 1.0 NA 3 <br />Cd, Dis u 1 4 0 0 0 0 6.2 3 <br />Cr, Tot u /1 16 1.3 11 26 15 NA 3 <br />Cu, Dis u 1 2 1.5 5.0 8.5 5.0 29 1,3 <br />Fe, Dis u 1 15 71 100 129 101 NA 1 <br />Pb, Dis u l 3 0 0 0 0 11 1,3 <br />Mn, Dis u 1 18 0 9.5 12 7.6 2618 1 <br />H , Tot u 1 46 ND ND ND ND 0.01 2 <br />Ni, Dis u 1 5 0 0 0 0 168 1,3 <br />Se, Dis u 1 7 0.90 1.0 1.1 1.0 4.6 1,3 <br />A, TR u 1 2 0 0 0 0 NA 4 <br />Zn, Dis u 1 5 0 10 18 10 382 3 <br />Note 1: When sample results were below detection levels, the value of zero was used in accordance with the Division's standard approach fo <br />summarization and averaging purposes. <br />Note 2: For [he noted parameters, data were found at less than detection levels. The detection levels, however, were greater than the in-strea <br />standards. In accordance with Division procedures, no determination of water quality is made when the detection levels are greater than the in <br />stream standards. <br />Note 3: Samples were collected from USGS station 09244464, Hubberson Gulch near Hayden, CO <br />Note 4: Samples were collected from USGS station 09060500, Rock Creek near Toponas, CO <br />To establish Qe~and Me~-at Outfalls 004 and 007, monthly average effluent concentrations available <br />from PCS for flow, total recoverable iron, dissolved manganese and total mercury were used. PCS <br />data for these parameters for a period of record from October 1998 through September 2000 were <br />obtained and averaged. The average concentrations for each month were then determined and were <br />used as the Qe~and Mel: <br />Data for other parameters were not available and it was not appropriate to assume an effluent <br />concentration equal to zero. Absent effluent data for the remaining parameters, the Division <br />procedures are to forgo calculations of BWQ concentrations until such time as comparable data are <br />available. For this reason, the antidegradation review henceforth only covers total recoverable iron, <br />dissolved manganese and total mercury. <br />For Outfa11004, the BWQ concentration is equal to the Mews previously discussed. A summary of <br />these values is provided in Table A-9. Pursuant to the approach discussed above, the equation for <br />BWQ, and the available data, the BWQ concentrations for potential pollutants of concern are set <br />forth in Table A-10 for Outfa11007. <br />Appendix A 1wQn ea version a-s FABL> Page 15 of 19 Last Revised September 2, 2005 <br />